JP3187548B2 - Reproduction binarized pulse correction method in mark edge recording / reproduction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a playback binary pulse correction how put the mark edge recording and reproducing system of the optical disk drive apparatus or a magneto-optical disk drive device.

[0002]

2. Description of the Related Art In general, when data is written on an optical disk, a laser beam is irradiated onto an optical recording medium to apply heat, thereby making a hole in the medium, inverting the magnetization direction of the medium, or writing data on the medium. By changing the crystal state,
The data is recorded.

[0003] Here, as one of the recording methods of the optical disk, a "mark edge recording method" in which a code bit is made to correspond to each of a front edge and a rear edge of a recording mark so that the length of the recording mark carries information. There is. That is, as shown in FIG. 7, this is a recording method in which the recording density is improved by recording two modulation bits on one recording mark. As the recording data pattern, the modulation code is NRZ
It is converted into I (Non Return to Zero Inverted) code data and recorded on an optical disk. Further, at the time of data reproduction, as shown in FIG. 7, binarization is performed by detecting edge positions corresponding to the rising and falling edges of the NRZI code data of the reproduction signal obtained from the optical disk.

[0004] As a binarization method, as shown in FIG.
The comparator 1 compares the level of the reproduction signal from the optical disk with the level of a preset threshold Th, detects the rising and falling edges with the edge pulse detector 2, and performs the binarization pulse. There is something to get. As shown in FIG. 9, there is also a configuration in which a second-order differentiating circuit 3 performs a second-order differentiation on a reproduced signal from an optical disc and then passes a ground-referenced comparator 4 to obtain a binarized pulse. See JP-A-2-137128).

Although this mark edge recording method is suitable for high-density recording, it requires an accurate edge position. That is, when data is recorded on an optical disk by the mark edge recording / reproducing method, due to the effect of heat conduction of the optical disk or the like, as shown in FIG. 10, the length is different from the actual recording pulse and the mark shape is irregular. May occur. This phenomenon becomes more remarkable in a medium having a high thermal conductivity such as a magneto-optical disk. As a result, if the conventional binarization method is used, the edge position cannot be detected correctly, which is a main cause of a data reproduction error.

Therefore, as shown in FIG. 11, the length of a recording mark to be actually recorded is controlled by performing a recording pulse correction of intentionally shortening all recording pulses and recording data. Japanese Patent Application Laid-Open No. 63-29336 discloses an arrangement in which an ideal mark length is approached.

[0007]

However, in practice,
Although it is important how to calculate such an optimum correction value for the recording pulse correction, it has not been mentioned up to this point in the related art. Furthermore, even if the length of the recording mark can be controlled to the ideal mark length by the recording pulse correction by some method, for example, the leading edge side of the recording mark is shortly after laser beam irradiation is started. Since the conduction of heat to the recording layer of the optical disk tends to be delayed, the mark shape is irregular in the case of FIG. 11 as in the case of FIG. 10, and as a result, the edge position detection is also shifted as indicated by Δ. Is caused.

[0008]

[0009]

[0010]

According to the first aspect of the present invention,
Is a binarized pulse in the mark edge recording / reproducing method.
As a data correction method, the NR of the optical recording medium at the time of reproducing information is
Playback signal from area where ZI code data is recorded
Binarized pulse obtained by delaying the binarized pulse of
And the binary pulse and the delayed binary pulse
Select either the logical sum output or the logical product output of
Output as a binarized pulse after positive, and binarize
Setting of delay amount to delay pulse for a predetermined time and logical OR operation
The selection between force and AND output can be made by changing the recording mark length when recording information.
Optical recording medium while performing recording pulse correction to control
From the area where the NRZI code data of the body is recorded
The midpoint between the positive and negative peak values of the playback signal and this
Difference between reproduced signal and signal after passing through Nth-order low-pass filter
And the information to be recorded on the optical recording medium in order to calculate the magnitude of such a difference and its positive / negative polarity in each sector of the optical recording medium immediately before the data area. The continuous pattern data recorded in the VFO area arranged in the.

Further, according to the second aspect of the present invention, the VFO
The calculation of the magnitude of the difference using the continuous pattern data recorded in the area and its positive / negative polarity shall be performed for each sector or for each of a plurality of sectors at the time of information reproduction. Based on this, the setting of the delay amount and the selection of the logical sum output and the logical product output are performed in units of each sector or a plurality of sectors.

According to the third aspect of the present invention, there is provided the first aspect.
In the invention described above, setting of a delay amount and selection of a logical sum output and a logical product output based on the final information of the magnitude of the difference calculated when obtaining the optimum value of the correction amount of the recording pulse correction and its positive / negative polarity To do.

[0013]

[0014]

[0015]

[Action] In the invention 請 Motomeko 1, wherein the reproduced signal
Generates a delayed binarized pulse obtained by delaying the binarized pulse for a predetermined time.
Of the original binarized pulse and this delayed binarized pulse
Binarized pal with one of logical output and logical product output corrected
The edge position included in the original binarized pulse
It is possible to perform proper reproduction by removing the detection error component of the position,
At this time, setting of the delay amount for the delay binarized pulse and
Selection between logical sum output and logical product output is complemented by recording pulse correction.
The magnitude of the difference and its positive and negative electrodes for adjustment of the positive amount
The original binarization pattern of the reproduced signal.
Detection deviation amount and detection deviation method of edge position included in
Direction, that is, whether the recording mark is too long or too short.
You can really know. Therefore, the binarized pulse of the reproduced signal
Error can be corrected optimally
Since the information used to calculate the magnitude of the difference and its positive / negative polarity is a continuous data pattern recorded in the VFO area, the condition most susceptible to heat or the like accumulated during information recording. The difference calculation is performed below, and the detection shift correction of the edge position included in the binarized pulse of the reproduction signal can be more reliably performed.

Further, in the invention according to claim 2 ,
As described above, the difference calculation is performed based on the continuous data pattern recorded in the VFO area. The difference calculation is performed for each sector or a plurality of sectors at the time of data reproduction, and the delay amount is calculated for each corresponding sector or a plurality of sectors. Since the setting and the selection of the logical sum output and the logical product output are performed, it is possible to correct the detection deviation of the edge position included in the binarized pulse of the reproduction signal in real time during data reproduction.

Further, in the invention according to claim 3 , the magnitude of the difference calculated when the optimum value of the correction amount of the recording pulse correction is obtained and the final information of the positive / negative polarity are used.
Since the delay amount is set and the logical sum output and the logical product output are selected, there is no need to perform a difference calculation process again to correct the binarized pulse during information reproduction. This makes it possible to optimally correct the detection deviation of the edge position included in the pulse.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. First, N is determined by the mark edge recording method.
A peak detector 5 to which a reproduced signal from an optical recording medium (not shown) in which RZI code data is recorded is input, and N
A next LPF (low-pass filter) 6 is provided.
Here, the peak detector 5 includes a positive peak detector 7 for detecting a positive peak value and a negative peak detector 8 for detecting a negative peak value. Outputs of these positive and negative peak detectors 7 and 8 are input to a midpoint detector 9. Further, a subtracter 10 is provided which receives the midpoint Vm detected by the midpoint detector 9 and the output Vs of the N-order LPF 6 and calculates a difference ΔV between the two.

In such a configuration, the reproduced signal from the optical recording medium is input to the positive and negative peak detectors 7 and 8, and a positive peak value and a negative peak value in the reproduced signal are detected. These peak values are input to the midpoint detector 9 and
A midpoint Vm between the negative peak values is detected and output. On the other hand, the reproduced signal is also input to the Nth-order LPF 6, and is converted into an output Vs. Here, the order N of the Nth-order LPF 6 is represented by the output Vs
May be determined so as to satisfy the design tolerance. Next, the difference ΔV between the midpoint Vm and the output Vs is calculated by the subtractor 10. That is, ΔV = Vs
−Vm, which is information including the magnitude of the difference and its positive / negative polarity. Such difference information (size and polarity)
Based on the above, it is determined whether or not the correction amount of the recording pulse correction at the time of recording is appropriate, and the correction amount is increased or decreased.

This will be described with reference to FIG. First, FIG. 2A shows ideal recording pulses, recording marks, and reproduced signals. On the other hand, FIG. 2B shows that the mark length is considerably long because the correction amount at the time of recording is too small. In this case, the midpoint Vm and the output Vs
And a difference ΔV is generated between them, and the positive / negative polarity is Vm
> Vs. FIG. 11C shows a case where the reproduced signal has some distortion due to the irregular shape of the recording mark, but the correction amount at the time of recording seems to be optimal, and the difference ΔV is almost 0. Further, FIG. 3D shows that the mark length is considerably shortened because the correction amount at the time of recording is too large. In this case, the difference ΔV between the midpoint Vm and the output Vs
And the positive / negative polarity is Vs> Vm, contrary to the case of FIG.

Therefore, the three modes shown in FIGS. 4B to 4D can be determined according to the magnitude of the difference ΔV and the positive / negative polarity, and the increase / decrease adjustment is performed so that the correction amount becomes appropriate. It can be understood that it can be done.

By the way, as the recording data for calculating the optimum correction amount of the recording pulse correction, code data which is most susceptible to heat or the like accumulated during recording among the modulation codes used is used. What is necessary is just to use a continuous pattern. For example, the code to use is
(1, 7, 2, 3) RLL (Run Length Limited)
Is adopted, continuous data of “10101010...” Which is the shortest pattern (short cycle repetition pattern) or the longest pattern (long cycle repetition pattern)
May be used as continuous data of "100000000010000000001 ...".

Further, the difference detection for calculating the optimum correction amount of the recording pulse may be performed using continuous data based on a combination of the shortest pattern and the longest pattern irrespective of one of the patterns. In the case of such a combination pattern, the difference is calculated under a condition close to when the user data is actually recorded.

Further, such processing for increasing or decreasing the correction amount of the recording pulse correction is learned so as to be repeatedly performed until the magnitude of the difference ΔV becomes equal to or smaller than a predetermined level and the correction amount is considered to be optimal. Is good. FIG. 3 shows such a learning algorithm.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, 2
The binarization pulse is appropriately corrected. First, a binary signal for converting a reproduction signal from an area of the optical recording medium in which NRZI code data is recorded into a binarization pulse Dp using a slice level. Circuit 11 is provided. The output side of the binarization circuit 11 is provided with a delay element 12 that delays the binarization pulse Dp by a predetermined amount of delay to generate a delay binarization pulse Dd. The binarization pulse Dp of these binarization circuits 11 and the delay element 1
An AND gate 13 and an OR gate 14 which receive the delayed binary pulse Dd by 2 as inputs are provided.
It is configured so that a logical sum is obtained. These AN
On the output side of the D gate 13 and the OR gate 14, there is provided a selector 15 for selecting one of the logical product output and the logical sum output based on the selector setting signal and outputting a binarized pulse Dr corrected. Is provided.

In such a configuration, even if there is a fixed shift such as an edge position shift due to mark shape irregularity that cannot be completely corrected by the recording pulse correction at the time of recording, it can be corrected at the time of data reproduction. This will be described with reference to FIG. First, when the actual recording pulse is recorded longer than the ideal binarized pulse as shown in FIG.
The delay binarization pulse Dd
And the output D obtained by ANDing with the AND gate 13
It can be seen that if _AND is selected by the selector 15 so that the corrected binarized pulse Dr is obtained, it becomes close to the ideal. On the other hand, if the actual recording pulse is recorded shorter, the binarized pulse Dp as shown in FIG.
Therefore, considering the delayed binary pulse Dd, OR
It can be seen that if the output _{DOR obtained} by the _OR operation at the gate 14 is selected by the selector 15 so as to obtain the corrected binarized pulse Dr, it becomes close to the ideal.

Further, a third embodiment of the present invention will be described with reference to FIG. This embodiment is different from the second embodiment in that
The setting of the delay time (delay amount) of the delay element 12 and the selection by the selector 15 are optional. In particular, the setting for increasing or decreasing the correction amount of the recording pulse correction described in the first embodiment is performed. The delay time is set and the selector 15 is selected based on the magnitude of the difference ΔV and the positive / negative polarity. Even in the case of this embodiment, even if the increase / decrease adjustment of the correction amount of the recording pulse correction at the time of recording is insufficient, it is possible to accurately correct the detection deviation of the edge position included in the binarized pulse at the time of data reproduction. Becomes

Here, the data for calculating the magnitude of the difference ΔV and the positive / negative polarity include the data for calculating the increase / decrease adjustment value of the correction amount of the recording pulse correction described in the first embodiment. The used data may be used as it is. Alternatively, at the time of actual data reproduction, continuous pattern data recorded in the VFO area located immediately before the data area in each sector on the format of the optical recording medium may be used. In this case as well, the difference ΔV is calculated under the condition most susceptible to heat or the like accumulated at the time of information recording, and the detection shift of the edge position included in the binarized pulse of the reproduction signal can be corrected with higher reliability. It will be.

It is assumed that continuous pattern data recorded in such a VFO area is used. At the time of data reproduction, a difference ΔV is calculated for each sector, and the difference ΔV calculated for each sector is calculated. Based on the size and the polarity, set the delay time for each sector and select
May be selected. Further, instead of each sector, a plurality of sectors may be used. In any case, real-time processing is performed during data reproduction.

On the other hand, as described in the first embodiment,
Based on the magnitude of the final difference ΔV calculated when the optimum value of the correction amount of the recording pulse correction is calculated and the polarity thereof, the delay time is set and the selector 15 is selected and designated. If the setting of the delay time and the designation of the selection by the selector 15 are held, the binarized pulse can be properly corrected without performing the process of calculating the difference during data reproduction. .

The setting of the delay time of the delay element 12,
The selection designation of the selector 15 may be executed by a command from the CPU, for example, or may be directly processed by hardware.

[0032]

[0033]

[0034]

Effects of the Invention] According to the invention 請 Motomeko 1, the reproduction signal
Binarized pulse obtained by delaying the binarized pulse of
And the original binarized pulse and this delayed binarized pulse
Binarized with one of the logical sum output and logical product output corrected
Pulse, so it is included in the original binarized pulse.
Appropriate reproduction that removes detection error components of edge positions
In this case, the delay amount for the delay binarized pulse
Record settings and selection between OR output and AND output
The magnitude of the difference used to adjust the amount of pulse correction
And its positive / negative polarity,
Edge position detection shift amount included in the initial binarized pulse
And the direction of the detection deviation can be known without fail.
Edge position detection error included in the binary pulse of raw signal
Can be optimally corrected, and the information used to calculate the magnitude of the difference and its positive / negative polarity is:
Since the continuous data pattern is recorded in the VFO area, the difference is calculated under the condition most susceptible to the influence of heat or the like accumulated during information recording, and the detection error of the edge position included in the binarized pulse of the reproduction signal is calculated. The correction can be performed with higher reliability.

Further, according to the second aspect of the present invention, the difference calculation is performed based on the continuous data pattern recorded in the VFO area as described above, but the difference calculation is performed for each sector or for a plurality of sectors at the time of data reproduction. Since the setting of the delay amount and the selection of the logical sum output and the logical product output are performed in each corresponding sector unit or a plurality of sector units, the edge included in the binarized pulse of the reproduction signal in real time during data reproduction. The position detection deviation can be corrected.

According to the third aspect of the present invention, the delay amount is set using the magnitude of the difference calculated when obtaining the optimum value of the correction amount of the recording pulse correction and the final information of the positive / negative polarity. And the output of the logical sum and the output of the logical product is selected, so that it is not necessary to perform the difference calculation process again for the correction of the binarized pulse at the time of reproducing the information, and it is included in the binarized pulse of the reproduced signal. This makes it possible to optimally correct the detection shift of the edge position.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining the operation.

FIG. 3 is a flowchart showing a learning algorithm.

FIG. 4 is a circuit diagram showing a second embodiment of the present invention.

FIG. 5 is a timing chart for explaining the operation.

FIG. 6 is a circuit diagram showing a third embodiment of the present invention.

FIG. 7 is an explanatory diagram for explaining the principle of the mark edge recording / reproducing method.

FIG. 8 is a circuit diagram showing an example of the binarization method.

FIG. 9 is a circuit diagram showing another example of the binarization method.

FIG. 10 is an explanatory diagram showing an irregular state of a recording mark.

FIG. 11 is an explanatory diagram showing a recording pulse correction method.

[Explanation of symbols]

 6 Nth-order low-pass filter Vm Midpoint Vs signal ΔV difference Dp Binarized pulse Dd Delayed binarized pulse Dr Corrected binarized pulse

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B ^7/ 00-7/013 G11B 7/125

Claims (3)

(57) [Claims] 1. A method for recording or reproducing information by irradiating a laser beam onto an optical recording medium in which tracks are formed in a spiral or concentric shape to form a recording mark whose length carries information. In the mark edge recording / reproducing method described above, a delayed binarized pulse is generated by delaying a binarized pulse of a reproduction signal from an area of the optical recording medium in which NRZI code data is recorded for a predetermined time during information reproduction, One of a logical sum output and a logical product output of the binarized pulse and the delayed binarized pulse is selected and output as a corrected binarized pulse.
Of delay amount for delaying a predetermined time and OR output
Selection of logical output and control of recording mark length when recording information
Optical recording medium while performing recording pulse correction for
From the area where the NRZI code data is recorded
The midpoint between the positive and negative peak values of the raw signal and this
The difference between the raw signal and the signal that has passed through the Nth-order low-pass filter
It is based on the size and its positive and negative polarity,
The optical recording medium to calculate the size of
The information to be recorded on the medium is decoded in each sector of this optical recording medium.
Is recorded in the VFO area located immediately before the data area.
A reproducing binary pulse correction method in a mark edge recording / reproducing method, wherein continuous pattern data is used. 2. The method according to claim 1, wherein the calculation of the magnitude of the difference using the continuous pattern data recorded in the VFO area and its positive / negative polarity is performed for each sector or for each of a plurality of sectors at the time of reproducing the information. is a based on its positive and negative, mark edge recording according to claim 1, characterized in that to perform the selection of the configuration and the logical sum output and the logical product output of the delay amount in each sector unit or sector unit Reproduction binarized pulse correction method in the system. 3. A delay amount setting and a selection between a logical sum output and a logical product output based on the final information of the magnitude of the difference calculated when obtaining the optimum value of the correction amount of the recording pulse correction and its positive / negative polarity. binarized reproduction pulse correction method in the mark edge recording method according to claim 1, characterized in that to perform the.